In the case of a box, whose German patent number is No. 613 158, of a similar kind, the tongue is placed into a slit of the outer box by its free end, inside which it can move until, when the inner box is lifted upward, it is stopped by an enlargement of its free end which does not fit through the slits; as the inner box is pushed further upward, it opens the folding lid. This arrangement of mounting the tongue to the outer box is difficult to carry out in practice because, at the time of assembly of the box, the tongue can be placed into the slit only with difficulty and by bending it. This cannot be done on modern packaging equipment without considerable expense.
In German Pat. No. 1 536 280 there is shown a box whose folding lid can be lifted; the lower end of a tongue is bent upward into a hook, which, when the inner box is lifted upward, grabs hold of a counterhook which is created by bending the upper border of the outer box. In order for the two hooks to get hold of each other, they have to be much thicker and otherwise dimensioned to perform the necessary functions. This arrangement tends to cause buckling of the upper rim of the back wall.
In U.S. Pat. No. 2,990,994 there is shown a box with a folding lid which can be opened; its inner and outer box consists of one cardboard cutting only. For the back wall of the outer box two cardboard layers are provided; the inner one joins at the top with the folding lid of the inner box, the outer one joins below in a fold with the inner one. In the area of the fold the outer cardboard layer of the back wall is flexible. If the inner box is pushed upward, the flexible area is first pulled through on the inside, then the folding lid is raised. Due to the double cardboard layer of the back wall additional cardboard is needed which makes the box unnecessarily thick. Also, the flexible area which is visible from the outside makes this box unattractive.
In a further development of this box, as shown in U.S. Pat. No. 3,977,520, the flexible area has been covered on the outside by an additional third cardboard layer for the back wall of the outer box. This means an even larger amount of cardboard and increased thickness of the package.